Polished rod lubricator



Oct. 10, 1961 w. B. THOMAS 3,003,583

POLISHED ROD LUBRICATOR Filed Sept. 21, 1959 BEA INV EN TOR. Wm L/:4M 5.T-xoMA 5 3,003,583 POLIEiHEl) ROD LUBRICATOR William B. Thomas, Rte. 2,Wellston, Oldm, assigno of fifty percent to Herman Thomas, Shawnee,Okla. Filed Sept. 21, 1959, Ser. No. 841,194 8 Claims. (Cl. 184-65) Thisinvention relates to improvements in lubnicators for oil Well polishedrods.

As it is well known in the oil industry, the majority of oil wellsrequiring pumping means for removing oil from the well utilize areciprocating-type pump supported in the lower portion of the well andoperated by a string of rods extending from a prime mover at thesurface. Such pumps are commonly known as sucker rod pumps and theuppermost rod of the string of rods is a specially constructed,smooth-surfaced rod which is commonly known as a polished rod. Thepolished rod extends through a stufiiing box at the well head which isdesigned to prevent leakage of the oil at the well head and to directthe pumped oil through a flow line from the well head to suitablestorage facilities.

During anormal operation of a sucker rod type of pumping installation,the oil being produced from the Well is present directly below thestufiing box, and the polished rod is moved in and out of this oil as itreciprocates through the stufiing box. The crude oil is normally at asubstantially constant temperature, and therefore retains the polishedrod at a SubStantiallycOnstant temperatur as well as providinglubricationfor the packing rings in the stufling box. However, the crudeoil contains an appreciable portion of foreign matter which invariablyenters the stufiing box when the polished rod is not otherwiselubricated, and provides an increased wear of the packing rings, also,the crude oil is not ordinarily the best lubricant for the packingrings. Therefore, operating personnel must frequently visit a producingwell and tighten the packing rings in the stufiing box to prevent aleakage of the crude oil through the stufiing box and onto equipmentaround the well head.

Many oil wells do not have sufficient capacity for a sustained operationof the sucker rod pump, such that all of the available oil in a well isfrequently removed by the pumping installation before the pump is shutdown by operating personnel. When no crude oil is available in the upperportion of the well for contact with the polished rod, the polished rodbecomes dry and substantial friction is encountered during reciprocationof the polished rod through the stuffing box. As a result, the polishedrod will burn out the packing rings in the stuffing box in a relativelyshort period of time and will then come in contact with metallicportions of the stufiing box to cause grooves or dents in the polishedrod, which in turn reduces the efficiency of the polished rod forsubsequent pumping operation, and frequently requires replacement of thepolished rod. Another situation which is frequently encountered is aparting of the sucker rod string during a pumping operation. In thislatter event, the prime mover at the surface of the well will normallyoperate at an increased speed to reciprocate the dry polished rodthrough the stufiing box and result in damage both to the stuffing boxand the polished rod, substantially in the same manner as when the pumpis operated with the well in a 'dry condition and as described above.

Prior workers in the art have designed variousdevices for lubricating apolished rod, but none have been widely accepted in the oil industry.Generally speaking, these prior devices utilize a container supported onthe upper end of the stufling box in such a manner as to provide acontinuous flow of lubricating oil to the polished rod. When thecontainer is of a practical size, it requires a United States Patent icefrequent resupplying of the lubricating oil to provide an effectivelubricating operation.

The present invention contemplates a novel lubricating devices which isadapted for attachment to a polished rod above the stuffing box andwhich provides lubrication of the polished rod in accordance with thetemperature of the polished rod, thereby minimizing the supply oflubricating oil which must be retained in the device, and assuring thatthe polished rod will remain lubricated in the event the well pumps dry,or in the event the sucker rods part. Broadly stated, the presentinvention may be defined as a device for lubricating an oil wellpolished rod in accordance with the temperature of the polished rod,comprising a body formed out of a heat conducting material, said bodyhaving an upper end and a lower end and having its inner face curved tomate With a portion of the periphery of the polished rod, said body alsohaving an aperture extending transversely therethrough and a groove inthe inner face thereof extending from said aperture to the lower end ofthe body, means for clamping the body to the polished rod, a containercarried by the body having an outlet in the lower portion thereof, asupply of lubricating oil in the container characterized by having itsviscosity change in inverse relation with respect to its temperature, ahorizontally extending conduit connected to the body and the containerproviding communication between said outlet and said aperture and beingformed out of a heat conducting material to retain the temperaturethereof substantially equal to the temperature of the polished rod, anda restriction in said conduit for-med of a heat conducting material andhaving an orifice therein of a size to control the flow of thelubricating oil therethrough in accordance with the temperature of thepolished rod.

An important object of this invention is to decrease the manualattention required for servicing oil Wells, and particularly theservicing of oil well stufiing boxes.

Another object of this invention is to increase the service life ofstuffing box packing rings. 7 T

A further object of this invention is to increase the service life ofoil well polished rods.

Another object of this invention is to provide lubrication of a polishedrod in accordance with the operating temperature of the polished rod.

A still further object of this invention is to provide a polished rodlubricator which has no moving parts, for simplicity of construction;requires no source of energy 'for operation, other than heat from thepolished rod;

will have a long service life, and may be economically manufactured.

Other objects and. advantages of the invention will be evident from thefollowing detailed description, when read in conjunction with heaccompanying drawings which illustrate my invention.

In the drawings:

FIGURE 1 is a top view of a lubricator constructed in accordance withthis invention illustrating the lubricator installed on a polished rod,and with the polished rod shown in section.

FIGURE 2 is a sectional view as taken along lines 22 of FIG. 1, with thepolished rod and the clamping means for holding the lubricator on thepolished rod being removed for simplicity of illustration.

FIGURE 3 is a front elevation view showing the inner face of the body ofthe lubricator which is clamped onto the polished rod.

FIGURE 4 is a sectional view similar to a portion of FIG. 2 andillustrating a modified construction.

Referring to the drawings in detail, reference character 10 generallydesignates a lubricator constructed in accordance with this inventionand which includes a body 12 adapted to be clamped around the polishedrod 14 of a well pumping installation by means of a U-bolt 16. The body12 is formed of a heat conducting material, such as bronze, and isconstructed in the shape of a saddle, with its inner face 18 curved tomate with the surface of the polished rod 14. It may also be noted thatthe body 12 is of a width to extend slightly less than half way aroundthe polished rod 14. Apertured flanges or ears 2% are formed at theopposite sides of the body 12 to receive the end portions of the U-bolt16, such that the body 12 may be calmped onto the polished rod 14 upontightening of the nuts 22 which are threaded onto the end portions ofthe U-bolt 16 into contact with the flanges 20. As previously indicated,the body 12 is clamped onto the polished rod 14 above the stuffing box(not shown) of a well pumping in stallation a sufficient distance thatthe body 12 will not contact the stufiing box during reciprocation ofthe polished rod 14.

As shown in FIGS. 2 and 3, an aperture 24 extends transversely throughthe central portion of the body 12 to provide a passageway forlubricating oil to the polished rod 14, as will be described. Also, avertical groove 26 is formed in the inner face 18 of the body 12 andextends from the aperture 24 to the lower end 28 of the body to conductlubricating oil from the aperture 24 downwardly along the polished rod14. Additional grooves 30 are also preferably provided in the inner face18 of the body 12 extending at an angle from the aperture 24 downwardlyand outwardly to the lower end 28 of the body on opposite sides of thegroove 26 to further distribute the lubricating oil around the polishedrod 14.

A coupling 32 is formed on the outer face 34 of the body 12 in such aposition that the bore 36 through the coupling communicates with theaperture 24. In the preferred embodiment, the aperture 24 is positionedat the upper end portion of the bore 36, for purposes which will behereinafter described. A restriction 38 is secured in the outer endportion of the coupling 32, as by threads, and is also secured in theouter end of a conduit 40 extending from the lower end portion of acontainer 42. The restriction 33 is also formed of a heat conductingmaterial, such as bronze. An orifice 44 extends longitudinally throughthe center of the restriction member 38 to control the flow oflubricating oil through the aperture 24, as will be described.

The container 42 is provided to retain a supply of lubricating oil 46therein which is characterized by having its viscosity change in inverserelation with respect to its temperature. In other words, when thetemperature of the oil 46 decreases, the viscosity thereof increases,and vice versa. The lubricating oil 46 is discharged from the container42 through an outlet 48 in the lower end portion of the container. Theconduit 40 is suitably secured to the container 42 concentrically aroundthe outlet 48. It may also be noted that the outlet 48 is preferablypositioned slightly above the bottom 50 of the container 42, such thatany foreign matter which may be in the lubricating oil will settle outinto the extreme lower end portion of the container and will not flowwith the oil through the outlet 43. Finally, a suitable cap 52 issecured over the upper end of the container 42 in any desired manner,such as by the use of threads 54. However, the cap 52 should not besecured air tight over the upper end of the container 42, since the oil46 gravitating through the outlet 48 must be easily replaced by air, aswill be readily understood by those skilled in the art.

Operation As previously indicated, the device is clamped to the polishedrod 14 a sufficient distance above the stuffing box, such that thedevice 10 will not contact the stufiing box during reciprocation of thepolished rod. When the device 10 is first secured on the polished rod 14and the container 42 is filled with the lubricating oil 46, or when thepolished rod 14 is not operating and is at normal atmospherictemperature, a portion of the lubricating oil will fiow through theoutlet 48, conduit 40, orifice 44, bore 36 and aperture 24 into grooves26 and 30 to provide an initial lubrication of the polished rod 14.

During a normal operation of the polished rod 14, the polished rod willrun at a substantially constant temperature, as previously indicated.Since the body 12, coupling 32 and restriction member 38 are constructedof a heat conducting material, the temperature of these components willbe substantially equal to the temperature of the polished rod 14. Thesize of the orifice 44 and the characteristics of the lubricating oil 46are preferably selected such that either no oil, or only a minimumamount of oil, will flow through the orifice 44 when the polished rod'14- is operating in a normal manner. For example, the oil 46 may be aconventional 30 weight engine lubricating oil, and when the orifice is.016 inch in diameter, the oil will either not flow through the orifice,or will only drip slowly through the orifice, when the oil is at atemperature corresponding to the operating temperature of most polishedrods 14. It will be apparent that when no oil is flowing through theorifice 44, no oil will be supplied to the bore 36 in the coupling 32which forms a reservoir between the orifice 44 and the aperture 24.However, this reservoir is initially filled with oil, as previouslydescribed, such that a small quantity of lubricating oil will beimmediately available for discharge through the aperture 24 in the eventthe temperature of the polished rod 14 begins to rise. As thetemperature of the polished rod 14 increases, the oil standing in thereservoir 36 is heated and will expand to flow through the aperture 24into the grooves 26 and 30. As the temperature of the polished rod 14either 0ontinues to increase, or stay at an increased temperature, therestriction member 38 is also gradually heated up to heat the oilcongealed in the orifice 4'4 and provide a flow of the lubricating oilthrough the orifice 44 for continuous discharge through the aperture 24.

Any oil flowing through the aperture 24 will gravitate through thegrooves 26 and 30 to the respective portions of the polished rod 14. Asthe polished rod 14 is reciprocated through the stuffing box, thislubricating oil will come in contact with the upper end of the stufiingbox and will be adequately distributed around the entire periphery ofthe polished rod 14 to maintain lubrication of the polished rod in thestuffing box packing rings. Therefore, the packing rings will not becomeburned through the lack of lubrication, and will have an increasedservice life.

As an alternate construction, and as illustrated in FIG. 4, the coupling32 may be formed concentrically around the aperture 24 and therestriction member 38 may be threaded completely into the coupling 32 toabut the outer face 34 of the body 12. In this construction, the orifice44 is aligned with the aperture 24 to transfer lubricating oil directlybetween the orifice 44 and the aperture 24 when the temperature of therestriction member 38 is raised sufiiciently for a flow of thelubricating oil through the orifice 44. It may also be noted that theaperture 24 may, in this embodiment, be formed the same size as theorifice 44, since no oil will flow through the aperture 24 until the oilalso flows through the orifice 44. FIGURE 4 also illustrates that onlythe groove 26 may be used in the inner face 18 of the body 12 to conductthe lubricating oil downwardly along the polished rod when the oil flowsthrough the aperture 24. In all other respects, the embodiment shown inFIG. 4 is the same as the embodiment shown in FIG. 2.

From the foregoing, it will be apparent that the present inventionprovides a polished rod lubricator which has no moving parts, forsimplicity of construction; requires no source of energy for operation,other than heat from the polished rod; will have a long service life,and may be economically manufactured. When the device is constructed toprovide a constant application of lubricating oil on the polished rod, afilm of the lubricating oil will remain on the polished rod, even thoughonly a minor amount of the oil is used. As a result, a minimum of thecrude oil produced by the well will enter the stuffing box and increasethe wear of the packing rings, such that the field personnel will notneed to adjust the packing rings as frequently as in the present dayinstallations. In this connection, it may be noted that most oil wellsare produced only a portion of each 24-hour period, such that additionalamounts of lubricating oil will be supplied by the device ratherfrequently to maintain efiicient lubrication of the packing rings in thestufiing box. Also, if difficult conditions are encountered, the orificemay be of sufiicient size to provide an increased flow of thelubricating oil through the apparatus for increased lubrication of thepolished rod. It will also be apparent that the present device providesan appreciable lubrication of the polished rod in the event the polishedrod becomes heated, as by the well running dry or by a parting of thesucker rod string. Furthermore, since either no lubricating oil isconstantly drained from the present device, or only a minor portion ofthe lubricating oil is continuously drained through the present device,a minimum oil supply will be required and the container will not need tobe filled with lubricating oil, except during trips of the operatingpersonnel to a well for other operations, such as for starting the wellpumping installation.

Changes may be made in the combination and arrangement of parts orelements as heretofore set forth in the specification and shown in thedrawings, it being understood that changes may be made in theembodiments disclosed without departing from the spirit and scope of theinvention as defined in the following claims.

I claim:

1. A device for lubricating an oil well polished rod in accordance withthe temperature of the polished rod, comprising a body formed of a heatconducting material, said body having an upper end and a lower end andhaving its inner face curved to mate with a portion of the periphery ofthe polished rod, said body also having an aperture extendingtransversely therethrough and a groove in the inner face thereofextending from said aperture to the lower end of the body, means forclamping the body to the polished rod, 2. container carried by the bodyhaving an outlet in the lower portion thereof, a supply of lubricatingoil in the container characterized by having its viscosity change ininverse relation with respect to its temperature, a horizontallyextending conduit connected to the body and the container providingcommunication between said outlet and said aperture and being formed ofa heat conducting material to retain the temperature thereofsubstantially equal to the temperature of the polished rod, and arestriction in said conduit formed of a heat conducting material andhaving an orifice therein of a size to control the flow of thelubricating oil therethrough in accordance with the temperature of thepolished rod.

2. A device as defined in claim 1 wherein said restriction is positionedin spaced relation from said body to provide a reservoir between theorifice and said aperture.

3. A device as defined in claim 2 wherein said aperture is larger indiameter than said orifice and is positioned at the upper end of saidreservoir.

4. A device as defined in claim 1 wherein said restriction is positionedin contact with said body and said aperture and said orifice arealigned.

5. A device as defined in claim 1 wherein said body also has a pair ofslanting grooves in the inner face thereof extending downwardly andoutwardly from said aperture on the opposite sides of thefirst-mentioned groove.

6. A device as defined in claim 1 wherein said lubricating oil is aBSD-weight engine lubricating oil and said orifice has a diameter ofapproximately .016 inch.

7. A device for lubricating an oil well polished rod in accordance withthe temperature of the polished rod, comprising a body formed of a heatconducting material, means for clamping the body to the polished rod forretaining the body at substantially the same temperature as the polishedrod, a container carried by the body, a supply of oil in the containercharacterized by having its viscosity change in inverse relation to itstemperature, and means forming a passageway from the container to thepolished rod when the body is clamped onto the polished rod which is inheat conducting relation to said body, said last-mentioned means beingformed of a heat conducting material and having an orifice therein of asize to control the flow of the oil therethrough in accordance with thetemperature of the polished rod.

8. A device for lubricating a reciprocating rod in direct proportion tothe heat of the rod derived from its frictional contact with a packingseal through which it moves, comprising a heat-conducting body securedto said rod in heatconducting relation thereto for reciprocationtherewith, said body having an orifice extending from said rod throughsaid body of a size to control the flow of lubricant therethrough inaccordance with the temperature of the rod; a container having itsinterior in communication with said orifice; and a lubricant in thecontainer characterized by having its viscosity change in inverserelation to the temperature.

References Cited in the file of this patent UNITED STATES PATENTS1,162,586 Dutro Nov. 30, 1915 1,446,098 McNamara Feb. 20, 1923 1,712,006Moore May 7, 1929 2,479,349 Hagg Aug. 16, 1949

